Sensor element

a technology of sensor elements and elements, applied in the field of sensor elements, can solve the problems of increasing the heat dissipation resistance value over time, and the probability of pt disassembly is more likely to occur, so as to prevent or reduce the diffusion of pt, increase the lifetime, and increase the lifetime

US20180284050A1Active Publication Date: 2018-10-04NGK INSULATORS LTD
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2018-10-04

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Abstract

A heater part of a planar sensor element includes: a Pt heater element; and an insulating layer including 90-99.9 wt % of an insulating material having a different coefficient of thermal expansion from a solid electrolyte forming a base part of the element. The heater part other than a heater electrode is buried in the base part. The heater element has a thickness of 10-50 μm and is covered with the insulating layer. The insulating layer has a porosity of 4% or less and a thickness of 50-150 μm. The distances of the insulating layer from an end portion of the element, from a main surface on which the heater electrode is located, and from a side surface of the element are respectively 0.25-0.75 mm, 0.20-0.60 mm, and 0.20-0.60 mm. The total length of the element is 80.0 mm or less.
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Description

BACKGROUND OF THE INVENTIONField of the Invention

[0001] The present invention relates to a sensor element formed of an oxygen-ion conductive solid electrolyte, and, in particular, to the configuration of a heater included in the sensor element.Description of the Background Art

[0002] As an apparatus for measuring the concentration of a predetermined gas component (e.g., O2, NOx, HC, and CO) in a measurement gas, including a combustion gas and an exhaust gas in an internal combustion engine, such as an engine of a vehicle, a gas sensor including a sensor element formed of an oxygen-ion conductive solid electrolyte, such as zirconia (ZrO2), has been known.

[0003] As such a sensor element of the gas sensor (gas sensor element), a sensor element having a structure in which a sensor part for performing detection of a target gas component and the like and a heater part including a heater for heating the sensor part to activate the oxygen-ion conductive solid electrolyte forming the sensor part...

Examples

examples

[0119]A total of 21 types (all Examples and all Comparative Examples) of sensor elements 101 having different combinations of conditions to manufacture the insulating paste for forming the heater insulating layer 74, the porosity of the heater insulating layer 74, and the dimensions at the six locations of the sensor element 101 directed to the sensor element dimensional conditions (the thickness t1 of the heater insulating layer 74, the thickness t2 of the heater element 72, the end portion distance d1, the thickness direction distance d2, the side portion distance d3, and the total length L of the sensor element 101) were manufactured. For each of the sensor elements 101, a durability test was conducted through continuous heating using the heater part 70 for a long period of time, and the state after the test was evaluated.

[0120]As for the conditions to manufacture the insulating paste, a material species of Al2O3 (alumina) used as a material was set to be at two levels, and an ad...

examples 1 to 11

[0137]The material species of alumina was set to the material species “A”, and, regarding Example 1 as a reference, the porosity of the heater insulating layer 74 in Example 2 was set to have a value smaller than that in the other examples. The thickness t1 of the heater insulating layer 74 was set to be smaller in Example 3 than that in the other examples, and was set to be greater in Example 4 than that in the other examples. The thickness t2 of the heater element 72 was set to be smaller in Example 5 than that in the other examples, and was set to be greater in Example 6 than that in the other examples. The values of the end portion distance d1, the thickness direction distance d2, and the side portion distance d3 were set to be smaller in Example 7 than those in the other examples, and were set to be greater in Example 8 than those in the other examples. The value of the total length L of the sensor element 101 was set to be greater in Example 9 than that in the other examples. ...